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How to retrieve the values of specific variables at the nodes of your mesh?

It is sometimes necessary to retrieve the values of specific variables at the nodes of your mesh. This could be done by looping over cells/faces and accessing the interpolated data at the nodes.

The UDF (DEFINE_ON_DEMAND) included in this solution provides an example for accessing pressure data on the nodes of a boundary surface.
Before executing the UDF, please make sure:

1. Data is available (case is initialized/ solved/ data file is read)
2. The correct boundary zone ID is provided
3. The correct field variable name is provided

Source code is below:

/*****************************************************************************
* UDF to access field variable data at nodes for a face zone
* Written by Rajiv Rath (rlr@fluent.co.in)
****************************************************************************/

char *what = "pressure"; /* field variable name for which data is to be extracted */

/* For single phase cases, the names of the field variables can be obtained from FLUENT TUI mode.
Example: /display/contours/ => this lists all the field variables that are available. */

/* For multi phase cases, the names of the field variables can be obtained from FLUENT TUI mode.
Example: /display/contours/phase-x => this lists all the field variables (y) that are available.
The filed variable name = "phase-x-y" => x = phase number ( 1, 2 etc.), y = variable name displayed in TUI. */